From EP 0 882 561 A1 there is known a method for the production of a sound insulation molding with mass and spring, with which both the mass and the spring are produced from molded polyurethane. For the formation of a mass, reaction substances and fillers are sprayed or injected into a mold cavity and brought to reaction, whereby by means of a closed mold, there is attained a forming of the mass. After changing the lid of the mold, foam is then formed in the mold cavity, as a spring on the mass, and this by means of a second molding through which the mass layer is foamed on the back.
However, EP 0 882 561 A1 fails to recognize the high cost of tooling for the processes disclosed therein. As set forth above, a mold construction comprising a mold cavity with two separate (male) lids is required, one lid is required to form the backside of the mass, while the other lid is required to form the backside of the spring. Furthermore, as a result of having to use a single mold (female) cavity in combination with two lids, the cycle time essentially doubles with such use of the mold cavity. Thus, particularly for higher volume production, multiple sets of molds may be required due to the increased cycle time to meet production demand, further increasing tooling costs.
Furthermore, once the molds are formed, it is not possible to provide increased sound attenuation/damping in newly uncovered/discovered locations of the acoustic insulator requiring increased sound attenuation/dampening without modification of the molds. Thus, changes in the acoustic insulator on the fly from part-to-part are not possible.
What is needed in a method of producing an acoustic insulator which overcomes the high tooling costs and inability to quickly change a sound attenuation profile of the acoustic insulator of the art, particularly from one part to the next part to support high volume manufacturing.